RanSeed.h

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/*
  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
*/
 
 
#ifndef RanSeed_h
#define RanSeed_h
 
#include <cstdint>
 
extern "C" { uintptr_t ranseed_address_(); }

class RanSeed
{
public:
    RanSeed();
    ~RanSeed();
    
    int&    nseed  (void);
    
private: 
 
    struct RANSEED;
    friend struct RANSEED;
 
    struct RANSEED
    {
    int nseed;
    };
 
    static RANSEED* s_ranseed;
};
 
// set pointer to zero at start
RanSeed::RANSEED* RanSeed::s_ranseed =0;
 
inline
RanSeed::RanSeed()
{}
 
inline
RanSeed::~RanSeed()
{}
 
inline int&
RanSeed::nseed    (void)
{
    if (!s_ranseed) s_ranseed = reinterpret_cast<RANSEED*>(ranseed_address_());
    return s_ranseed->nseed;
}
 
#endif